gecko-dev/webtools/tinderbox2/Policies

To install Tinderbox2 you will need some information about your
existing computer systems and some idea about what your goals are.

Here is a list of topics to help get you started, some of these
ideas may not be appropriate for your environment.

Web server configuration
------------------------

The web server is what delivers the Tinderbox2 information to the world.
Web server configuration is a bit of an art and you will need to
understand the policies which are used to administer your web server.

  * You will need to decide the directory where Tinderbox2 should write
    the static HTML pages.  This will depend on how your web server is
    configured. The default location is based on the RedHat 7.1
    (apache-1.3.19-5) installation and is: /var/www/html/tinderbox2.

    You will also need to know what the URL browsers will need to use
    to find this directory. Since Tinderbox2 generates static web
    pages, it is possible to run Tinderbox2 and not run a web server.
    One way this could be done is if you have a network file system
    and all users have browsers which can read from the HTML directories.
    In this case all URL's should begin with "file:/" instead of the
    usual "http://".

  * Project level administration is done via cgi scripts.  These scripts
    allow administrators to set the message of the day, and the state
    of the tree (open, closed, restricted).  Also all users can post
    notices to the web pages via a cgi script.
      
    CGI programs are often restricted to a portion of the file system
    which is disjoint from the HTML files. You will need to figure out
    where the CGI programs will go.  Tinderbox2 takes its defaults from
    RedHat 7.1 and uses /var/www/cgi-bin/tinderbox2. You will also need
    to know what the URL browsers will need to use to find this directory.

  * CGI scripts will run as an un-authenticated user on your system.
    You will need to decide which user will run the Tinderbox2 CGI
    scripts. The same user id must be used for running the scripts as
    for Tinderbox2 mail delivery.

    The Tinderbox2 configuration files will define this user id and,
    as a security precaution, check that it is running as the required
    id.  It is suggested that this id not be a privileged id (higher
    ids are better, please make this number be greater than 10 and
    bigger than 100 is recommended). Smaller ids are often assumed to
    have more privileges on a Unix box than larger ids. It is not a
    good idea for an un-authenticated user to have any privileges so a
    large id is recommended.

    It is also recommended that you not use the id 'nobody' as this id
    is over used and it would be better to partition the un-authenticated
    user into separate ids in case of security problems.

    RedHat runs all its CGI scripts as the user 'apache', this is an
    acceptable user.  I would prefer to have a separate user to run the
    Tinderbox2 CGI scripts but this would require recompiling apache to
    enable suEXEC, and it is more effort than most groups can afford.

  * Tinderbox2 Files. There are other Tinderbox2 files which need to
    be placed on the web server.  These include libraries and non-cgi
    programs. You will need to decide where to place these files.
    Most users put them in /home/tinderbox2.

  * Tinderbox2 Data. Tinderbox2 stores its data in the file system.
    For security it is often a good idea to keep this data out of the
    HTML and CGI directories so that malicious users can not directly
    access this data.  The compressed build logs can grow quite large,
    so it is recommended to put the data on a file system with room.
    The default is to put them in the directory /home/tinderbox2/data.

Mail
----

Many of the Tinderbox2 modules (Bug Ticket, Build, CVS) receive their
data via mail.

  * The mail system on your web server machine must be configured to
    deliver the mail into the Tinderbox2 mail processing programs.
    You should spend some time understanding how your mail delivery
    system can be configured to allow user mail to be delivered into a
    program and how to set the user id under which this delivery occurs.

    If you do not wish to configure your mail delivery program then you
    can use fetchmail to pull the mail out of a mail box and push it into
    the programs on a periodic basis.  See the install page for details
    on different aspects about mailing systems.

Production Version Control
-------------------------

One of the biggest responsibilities which a "build master" has is the
requirement that all code should be reproducible.  That is that at
any point in the future, even more than one year later, the current
binaries should be able to be rebuilt byte for byte from sources.

This requirement can be broken down as follows:

  * The build machine must be reproducible.  

    You must be able to get back the same build machine configuration
    you had at any point in the past.  This means that all OS libraries,
    all header files, all compilers, all build tools (make, grep, sed)
    must have some mechanism to roll back.  It is common to use a backup
    of the build machine to reconstruct it.  Most OS will give you a
    list of the software packages which are installed on the machine and
    their version numbers.  Maintaining a the list of software packages
    which are installed on the machine and check it into version control.
    This allows you to compare the state of the build machine at any two
    points in time.
    
    It is considered a best practice to limit the amount of software which
    is available on the build machine.  A build machine with too much
    installed will only make it difficult to reproduce older builds should
    the need arise. A build machine should not have installed any web
    servers or graphical window managers on your build machine.  It should
    be clear that the build machine should not be the same machine where
    the Tinderbox2 server runs.

  * The build process must be reproducible. That is all the steps which
    are used to create the application must be reproducible.

  * Build Interface - You must be able to run exactly the same build
    process in the future including all commands with command line
    arguments, all environmental variables.  I recommend that the entire
    build process be viewed as something outside of the build master
    control.  Developers are responsible for ensuring that there is a
    simple build master interface to construct all the software products
    which go into a build.  Typically there is a Makefile in a standard
    place where the build master can run something like "make all; make
    install;" and be guaranteed that this will build the product.

    The build interface should be viewed as something which never changes
    and are part of the build machine, like the OS and are changed only
    rarely.  It is hard enough to track all the parts of the build process
    which are epected to change, let alone trying to track complex build
    procedures.

    The build procedures should have a standard interface. By keeping the
    build instructions in one Makefile which is checked into the same
    version control system as the sources; it is easy to recreate any
    previous build even if the commands used to build the software
    fluctuate rapidly between releases.  There must be a simple interface
    to construct the software which will hide all the complexity of the
    actual construction.  

  * Build Environment - The Makefile will code all the build commands
    and all the environmental variables (PATH, UMASK, LD_LIBRARY_PATH,
    CLASSPATH) needed to build the software though it may rely on some
    well defined command line arguments (PREFIX, CCFLAGS, JAVA_LIBS) to
    make these prematurely.  These command line arguments should not
    change between versions of the software but should be a fixed set of
    build parameters.

    The parameters may be needed to specify where some files are found
    on the build machine (Ideally the build machine is set up the same
    as developers machines so these directories can be hard-coded into
    the Makefile but often there is a need for some directories to be
    specified at build time) or where files are to be created/installed
    on the build machine (typically a subdirectory of /var/tmp but there
    may be several builds running at once and each will need a different
    directory) or what kind of build is being created.

    Each part of the build which needs a particular environmental variable
    set or a special header file in some path should have tests which
    ensure that the build environment is valid.  The build scripts could be
    installed on the build machine and started by running:
    "/etc/rc.d/init.d/build start". This would ensure that the build script
    does not rely on any build environmental variables which are set by
    logging into the build account and are thus not tracked and versioned.

  * Environmental safety issues.  If the build environment can not be used
    to build the software then a human readable error message should be
    generated.  The Makefile can often run various checks on the environmen
    variables before they construct the code.  They check that all required
    environment variables are set, that the required libraries are found,
    that directories which must be disjoint (build and install directories)
    do not overlap.

    This test suite becomes a build regression test and as additional possible
    build problems are discovered, new tests can be added to the Makefile.
    It is a good habit to explicit set all environment variables so that there
    is no doubt as to their expected values.  It is important for the QA group
    to only use Builds which were created by an automated process so that you
    are sure that there are no undocumented steps in either the test builds or
    the released build.

  * Track the Build numbers.  Given a clean install of your product you
    should have all the information necessary to reproduce the executable
    from sources.  If a customer shows you the application binaries you
    must be able to get the source code which build the application,
    reconstruct the build machine which created the application and
    possibly rerun the build exactly the same way as the application was
    created before, this may include making some minor source code changes
    before the build is run.
    
    One method is to keep a file which contains:
      - The product release name
      - The sources 'as of date'. (Always checkout sources using
        a known datetime or revision # (cvs -D or svn -R) so that
        exactly the same sources can be recovered knowing only the
        'date/time' which was used to check them out.
      - The branch name
      - The module name.

    This can be stored as a file in the product (encrypted if necessary)
    or may be stored in some secure build master database where the data
    can be looked up by release name.  A good practice is to keep all data
    necessary to reproduce a build in the build output and delivered as
    part of the product.  This means that you can generate as many builds as
    needed automatically and not need to keep track of any of them.  When
    the QA team deems that a certain build is 'important', by making a
    particular build the official released copy then you can take a look at
    its contents and tag/branch the code at the sources which were used to
    build it.

  * Build Prefix: It is a good idea to familiarize yourself with the
    Makefile conventions regarding the make variable PREFIX.  It is
    easiest to understand if you think about what RedHat does when they
    build their distribution of RPM's but this will apply in many
    different systems including the Andrew File System (AFS) and most
    packaging systems.

    This variable is used during the build process
    "make all PREFIX=/home/apache" to tell the package where it will be
    installed (examples include /usr, /usr/local, /home/apache).  Reading
    a few RedHat Spec files to see how this works in practice.  The
    application may need to hard-code this value into its object code.
    When the application is installed it must not be installed into its
    proper place on the build machine.  The package that is being
    constructed could cause the build machine to stop working
    correctly if it is a buggy version of a system library or major OS
    application.  Instead the Makefile will install "make install
    PREFIX=/var/tmp/build-root/home/apache" the package into some other
    directory with a similar tree structure to its final destination.

    The packaging system will then move the files into the correct place
    during an installation step on the target machine.  The installation
    step only moves files and sets permissions.  The Makefile is not
    supposed to use the installation directories to hard code values into
    the application since the application will never be run from this
    installation directory.

    The hard part of the build, including any PREFIX magic, is in the
    build section.  Notice the clear separation between build/target
    machine, installation on the build machine, installation on the target
    machine, construction of the application binaries and installation of
    the application binaries.

    This is one of the reasons why building an application on a build
    machine is different from the way in which developers build their code
    on their personal development machines.  This PREFIX issue will arise
    when you try and build the Tinderbox2 system and also when you
    construct the Makefiles for your own application.  Since the build
    machine is not the target machine it can not be assumed that files
    will always be in the same places on both (for example Perl.)

  * Application Architecture.  The build process should mimic the
    architecture of the code.  It should be a final test that the code
    was coded to the same specifications that it was designed.  It is a
    common problem for code to turn into spaghetti with each piece of
    code using functions and creating dependencies on every other piece
    of code.

    For example it is probably a mistake for code in the database
    abstraction layer to be implemented in terms of code in the HTML
    generation layer.  These two libraries should probably be independent
    of each other, though they both might depend on a common string library.
    The code architecture should limit the dependency graph between code
    modules.  The Build Master must enforce the restrictions on information
    flow between components. Thus no libraries should be in the path unless
    the architecture allows this module to depend on those libraries.

    The architecture must not have circular dependencies.  Circular
    dependencies not only make upgrading individual libraries difficult
    but also make testing components nearly impossible.  That is it should
    be possible to build some set of libraries L0 which depend on no
    libraries and then build some other set of libraries L1 which depend
    only on L0 libraries then build L2 which depend only on the L0 and L1
    libraries.  This "build chain" will prevent circular dependencies and
    help keep your code testable and the dependencies understandable.
    More information about why this is a good practice is available in
    "Large-Scale C++ Software Design" (Addison-Wesley Professional
    Computing Series) by John Lakos

    You should enforce the convention that developers are not allowed to
    overload standard system libraries.  Always put standard libraries
    in the path before any library our company develops.  Build the
    application in stages to ensure that parts of the application which
    are not intended to depend on other code will not have other header
    files on the build machine at the time that they are constructed.
    Build dependencies between modules which are expected are explicitly
    controlled with build scripts and version numbers.